This invention relates to the improvement of fish culture through control of the sucker and stickleback by treating its aquatic habitats with diethyl esters of phosphoric, phosphorous, thiophosphoric and thiophosphorous acid that contain a chloride or a chlorinated ethyl or vinyl group.
Selective toxicants are beneficial because they eradicate pest fish without harm to natural stocks of desirable species. They alter the balance between predator and prey which enhances biological control of the pest species.
Suckers have always been abundant. Sixty-five species of suckers exist in North America. Due to the construction of reservoirs, large shallow land areas have been flooded which provide ideal sucker habitats. This has enabled the sucker to thrive and greatly increase its range in tributary streams. Because of their large size, adult suckers have an exceptionally good rate of survival and form 80 to 95 percent of the weight of fish found in some streams. Suckers greatly reduce the populations of food for game fishes with which they compete, which usually are species of salmon and trout in western North America. The results are that resident trout and salmon are scarce where sucker populations abound. Because suckers have practically no value as a sport or commercial fish, they are considered a pest fish and constitute an aggravating problem wherever they exist in competition with desirable species of fish.
Five species of the stickleback family exist in North America of which the threespine stickleback (Gasterosteus aculeatus) is the most notorious pest. The threespine stickleback is almost circumpolar in distribution and is normally found in marine, brackish and fresh waters of the northern hemisphere.
The stickleback has a high reproductive potential; as many as 600 eggs have been found in one nest. The fact that the male guards the nest and newly hatched young enhances juvenile survival. The stickleback has the advantage of a much shorter generation time (one to two years) than most salmon and trout (two to seven years). This permits the stickleback to increase their numbers at a faster rate than salmonids and become extremely abundant. Furthermore, stickleback have an exceptionally high rate of survival since they take advantage of inshore areas where large predators are not commonly found.
Stickleback greater reduce the populations of food and game fishes, usually species of salmon and trout, with which they compete. Furthermore, it is a successful competitor for limited food supplies and attacks juvenile salmon and trout. The result is that trout and salmon are usually scarce where stickleback populations abound. Since stickleback have no value as a sport or commercial fish, they are considered a pest fish and constitute an aggravating problem wherever they exist in conjunction with desirable species of fish.
Spot poisoning of sucker and stickleback populations with general toxicants like rotenone and toxaphene has been ineffective in controlling sucker and stickleback numbers because any benefits are very temporary and such methods are often carried out at the expense of killing natural stocks of desirable species.
Generally the sucker and stickleback are most prolific in waters containing salmonids and other cold water fishes, whereas carp and bullhead catfish are more prolific in warm waters. Manmade introductions of carp and bullheads into salmonid waters has resulted in them becoming pest fishes. In many instances, introduced carp and bullheads have thrived and competed for food and space with valuable food and sport fishes. Where carp and bullheads dominate an ecosystem, salmonids are essentially excluded. In such cases when carp and bullheads are eradicated and the waters stocked with salmon and/or trout the salmonids thrive.
Often bullhead catfish are so prolific that they become stunted and parasitized. Sometimes they prey upon more desirable fish and compete with them for food. They generally are considered a pest fish in channel catfish ponds.
Accordingly, it is an object of this invention to protect the native populations of food and game fishes by the rapid and substantial reduction of sucker, stickleback, carp and bullhead catfish populations.
It is another object of this invention to provide a simple and economic means for the destruction of sucker, stickleback, carp and bullhead catfish in the immature and adult stages.
It is a further object of this invention to provide a poison which will effect a substantially complete eradication of sucker, stickleback, carp and bullhead catfish in any waters without causing significant harm to or mortality of game and food fish or other desirable aquatic species.
It is a further object of this invention to control the sucker and stickleback population by means of diethyl esters of phosphoric, phosphorous, thiophosphate and thiophosphorous acids that contain a chloride or chlorinated ethyl or vinyl group.
It is a further object of this invention to control the carp and bullhead catfish population by means of diethyl esters of phosphoric, phosphorous, thiophosphoric and thiophosphorous acids that contain a halide or a double halogenated ethyl or vinyl group.
It is a further object of this invention, although not a necessary part of it, to use activated carbon as a deactivator for derivatives of the organophosphates mentioned above to minimize the impact of these chemical compounds on desirable fishes and other organisms in the environment and in domestic water supplies.
It is a further object of this invention, although not a necessary part of it, to use potassium permanganate as a deactivator for derivatives of the organophosphates mentioned above to minimize the impact of these chemical compounds on desirable fishes and other organisms in the environment.